• BBC ME 2/5A test set: grumpy but amused all the same

    From SimonM@21:1/5 to All on Sat Sep 4 13:13:32 2021
    I have one of these delightful 'luggable' test
    sets, complete with the EMX panel and Varley (one
    day the grandchildren will ask me what the funny
    big dial with a ring of holes in it is for).

    But rotary dialling notwithstanding, the time has
    come: either it's fitted into a proper 19"
    enclosure or it goes - it's just too awkward to
    use in its half-a-suitcase form any more.

    But before I do that, I want it to stay safe
    whilst I construct something to fit it into, so I
    started looking for some screws to fit the rack
    ears (in the suitcase).

    "Hmm... I thought they were normally M5 or M6...
    gotta be M4 then, shirley..."

    Nope, although probably made some time around
    1985, the wretched thing is threaded to 4BA. I
    only had three (not four) suitable machine screws,
    but they will serve for now.

    To be fair, it's the suitcase that's the issue,
    not the rackable bits themselves, so it's only
    temporarily annoying.

    But at what point was E.D. supposed to have gone
    metric? I thought it was back in the 1970s.

    I can't remember when I bought something new with
    4BA (or any BA) threads - probably as a teenager
    around 1976...

    S.

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  • From charles@21:1/5 to SimonM on Sat Sep 4 13:54:16 2021
    In article <sgvntc$g38$1@dont-email.me>,
    SimonM <somewhere@large.in.the.world> wrote:
    I have one of these delightful 'luggable' test
    sets, complete with the EMX panel and Varley (one
    day the grandchildren will ask me what the funny
    big dial with a ring of holes in it is for).

    But rotary dialling notwithstanding, the time has
    come: either it's fitted into a proper 19"
    enclosure or it goes - it's just too awkward to
    use in its half-a-suitcase form any more.

    But before I do that, I want it to stay safe
    whilst I construct something to fit it into, so I
    started looking for some screws to fit the rack
    ears (in the suitcase).

    "Hmm... I thought they were normally M5 or M6...
    gotta be M4 then, shirley..."

    Nope, although probably made some time around
    1985, the wretched thing is threaded to 4BA. I
    only had three (not four) suitable machine screws,
    but they will serve for now.

    To be fair, it's the suitcase that's the issue,
    not the rackable bits themselves, so it's only
    temporarily annoying.

    But at what point was E.D. supposed to have gone
    metric? I thought it was back in the 1970s.

    My BBC Metric Pocket Book was published in 1977.


    I can't remember when I bought something new with
    4BA (or any BA) threads - probably as a teenager
    around 1976...

    S.

    Bay screws were 2BA - 4BA was for light switches.

    --
    from KT24 in Surrey, England
    "I'd rather die of exhaustion than die of boredom" Thomas Carlyle

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  • From charles@21:1/5 to charles@candehope.me.uk on Sat Sep 4 14:00:15 2021
    On 04 Sep, charles@candehope.me.uk wrote:
    In article <sgvntc$g38$1@dont-email.me>,
    SimonM <somewhere@large.in.the.world> wrote:
    I have one of these delightful 'luggable' test
    sets, complete with the EMX panel and Varley (one
    day the grandchildren will ask me what the funny
    big dial with a ring of holes in it is for).

    But rotary dialling notwithstanding, the time has
    come: either it's fitted into a proper 19"
    enclosure or it goes - it's just too awkward to
    use in its half-a-suitcase form any more.

    But before I do that, I want it to stay safe
    whilst I construct something to fit it into, so I
    started looking for some screws to fit the rack
    ears (in the suitcase).

    "Hmm... I thought they were normally M5 or M6...
    gotta be M4 then, shirley..."

    Nope, although probably made some time around
    1985, the wretched thing is threaded to 4BA. I
    only had three (not four) suitable machine screws,
    but they will serve for now.

    To be fair, it's the suitcase that's the issue,
    not the rackable bits themselves, so it's only
    temporarily annoying.

    But at what point was E.D. supposed to have gone
    metric? I thought it was back in the 1970s.

    My BBC Metric Pocket Book was published in 1977.


    I can't remember when I bought something new with
    4BA (or any BA) threads - probably as a teenager
    around 1976...

    S.

    Bay screws were 2BA - 4BA was for light switches.

    Correction: just looked: Bay screws were 0BA

    PS I've quite a few BA screws - I could post some if needed.-

    --
    from KT24 in Surrey, England
    "I'd rather die of exhaustion than die of boredom" Thomas Carlyle

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    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From SimonM@21:1/5 to SimonM on Sat Sep 4 13:17:00 2021
    On 04/09/2021 13:13, SimonM wrote:
    I have one of these delightful 'luggable' test
    sets, complete with the EMX panel and Varley (one
    day the grandchildren will ask me what the funny
    big dial with a ring of holes in it is for).

    PS: If anyone has service info on them, it would
    be a great help - I've got the TIs but they only
    detail the specs, obviously.

    To rack mount it neatly I have to disconnect the
    Varley panel from the rest and move at least one
    circuit board off the battery module.

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  • From Brian Gaff (Sofa)@21:1/5 to SimonM on Sun Sep 5 09:43:32 2021
    Well, We at Decca were using all sorts of threads back in the 80s, BA UNc/F Metric etc. The racks had cage nuts pushed into square holes in the side
    bits which of course you could change at will, ie, no permanent threaded
    bits at all. I know this as on empty bays they would work loose in transit
    and rattle around in the bottom of the cases. This was mainly marine
    equipment of course for systems monitoring bought in and integrated with
    Decca Navigator and the like so it often came with captive screws of uncertain thread sizes!

    Brian

    --

    This newsgroup posting comes to you directly from...
    The Sofa of Brian Gaff...
    briang1@blueyonder.co.uk
    Blind user, so no pictures please
    Note this Signature is meaningless.!
    "SimonM" <somewhere@large.in.the.world> wrote in message news:sgvntc$g38$1@dont-email.me...
    I have one of these delightful 'luggable' test sets, complete with the EMX >panel and Varley (one day the grandchildren will ask me what the funny big >dial with a ring of holes in it is for).

    But rotary dialling notwithstanding, the time has come: either it's fitted into a proper 19" enclosure or it goes - it's just too awkward to use in
    its half-a-suitcase form any more.

    But before I do that, I want it to stay safe whilst I construct something
    to fit it into, so I started looking for some screws to fit the rack ears
    (in the suitcase).

    "Hmm... I thought they were normally M5 or M6... gotta be M4 then, shirley..."

    Nope, although probably made some time around 1985, the wretched thing is threaded to 4BA. I only had three (not four) suitable machine screws, but they will serve for now.

    To be fair, it's the suitcase that's the issue, not the rackable bits themselves, so it's only temporarily annoying.

    But at what point was E.D. supposed to have gone metric? I thought it was back in the 1970s.

    I can't remember when I bought something new with 4BA (or any BA)
    threads - probably as a teenager around 1976...

    S.


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  • From SimonM@21:1/5 to charles on Sun Sep 5 11:53:16 2021
    On 04/09/2021 14:00, charles wrote:

    I can't remember when I bought something new with
    4BA (or any BA) threads - probably as a teenager
    around 1976...
    S.
    Bay screws were 2BA - 4BA was for light switches.
    Correction: just looked: Bay screws were 0BA

    PS I've quite a few BA screws - I could post some if needed.-

    -- from KT24 in Surrey, England "I'd rather die of
    exhaustion than die of boredom" Thomas Carlyle

    Thank you Charles - that's extremely kind but not
    necessary.

    You're spot-on about 4BA for electrical socket
    boxes - I think that's why we ended up with the
    odd 3.5mm metricized version.

    In the case of my test set, it's the "suitcase"
    that's the problem.

    The rack ears on each of the three components -
    test set, battery box (also containing the sweep
    generator), and the lines unit & Varley - are all
    standard size, and will take modern M6 cage nuts
    and machine screws.

    But the "suitcase" seems to have very non-standard
    flanges inside, and it's these that are 4BA
    tapped. It's not a disaster, but they used really
    wide cheesehead screws. Ordinary 4BA will serve
    with washers, until I've made a proper desktop
    case for it.

    The rack flanges seem to be entirely original, but
    they might be specials, as there can't have been
    many made.

    The unit was intended for comms engineers on-site,
    and the suitcase lid held leads and a head &
    breast set/handset for use with the comms part,
    and possibly documentation. The lid and all its
    bits were missing on mine, but that doesn't really
    matter.

    Thinking about it, I suspect the suitcase company
    was asked to provide something to fit the ED
    units, and they probably hadn't found any need to
    switch to metric - 4BA would've been a sensible
    size for case locks, handles, etc. The corners of
    the suitcase are rounded (like motorbike luggage),
    and someone just rounded off the corners of the
    rack ears to fit the case. In a proper rack
    enclosure it will look really ugly as-is, but the
    corners can probably be concealed by an aluminium
    strip either side. It's well worth me spending the
    time to make it neat.

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